In the related art, an amplifying circuit including a main operational amplifier and a subsidiary operational amplifier is suggested to reduce an amplification error occurring due to finite gain of an operational amplifier. In the amplifying circuit, a virtual ground voltage of the subsidiary operational amplifier is amplified and is added to an output voltage of the main operational amplifier. As a result, gain of the main operational amplifier can be improved in an equivalent manner, the amplification error can be reduced, and amplification precision of the amplifying circuit can be improved.
However, in the amplifying circuit according to the related art, the amplification error occurs due to mismatching between the main operational amplifier and the subsidiary operational amplifier caused by a manufacturing variation of a semiconductor. In the amplifying circuit according to the related art, improvement of the amplification precision is limited by the amplification error.